The present invention relates to a dispenser, especially a hand-held spray dispenser in which a spray is emitted upon manual actuation of a valve.
For many years spray dispensers for dispensing products such as hair spray, deodorants, room air fresheners, etc., have utilized a container in which the product is stored in liquid form. A propellant gas under pressure occupies a head space between the top of the container and the liquid product. A dip tube extends downwardly through the propellant and product from a discharge valve located at the top of the container. When a user opens the discharge valve, the propellant pushes the liquid product into the bottom of the dip tube and then upwardly through the dip tube to the valve.
Propellant gases which have commonly been used have included butane and pentane, for example. Those gases feature the ability to become dissolved within the liquid product under the usual pressure conditions occurring within the container. Hence, the product is discharged in the form of liquid particles mixed with bubbles of the propellant gas. When exposed to the lower atmospheric pressure, those bubbles expand suddenly to advantageously break up the liquid particles into a finer spray pattern.
The conventional propellant gases have exhibited ideal product-expelling characteristics, i.e., an essentially constant pressure of a specified magnitude which can be maintained continuously for a specified duration of time.
More recently, however, due to concerns about environmental pollution, conventional propellant gases have fallen into disfavor. Alternative sources of propulsion have been sought which will satisfy the above-mentioned product-expelling characteristics without being accompanied by the discharge of polluting gases.
Dispensers have heretofore been proposed which employ an internal energy-storing member capable of being mechanically compressed by a rotatable actuator to pressurize a liquid product, e.g., see U.S. Pat. Nos. 3,195,168; 3,951,310; and 5,042,696.
In U.S. Pat. No. 3,951,310 there is disclosed an arrangement wherein a post extends vertically upwardly from a lower end of the container. The post is connected to a manually rotatable bottom cap of the dispenser so as to be rotatable therewith. The post extends through an energizing piston or follower member for rotating the latter. The energizing member is threadedly connected to an outer cylinder. As the cap and post are rotated, the piston is induced to move upwardly and compress an energy storing spring operatively disposed between the piston and the bottom of a product bag. This places the product under compression so that the product is expelled through a top valve when the latter is actuated. When the stored energy of the spring is depleted, the cap and post are again rotated to recompress the spring. However, it will be appreciated that in order for the piston to be able to travel upwardly sufficiently far to ensure that all or most of the product is expelled, the post must extend to a relatively high elevation within the dispenser. This means that the product bag must be provided with a relatively deep cavity at its lower end to receive the upper end of the post. The presence of this cavity serves to reduce the effective volume of the bag. Also the wall of the cavity must be reinforced to maintain its shape, thereby increasing the cost and complexity of manufacturing the bag.
It would, therefore, be desirable to provide a dispenser which does not appreciably reduce the effective volume of the product bag and which does not require bag cavity reinforcement.